Urethra

URETHRA
( Bull, Ram, Buck, Stallion, Boar, Dog, Rabbit, Cock )

Bull

  • It is a long mucous tube extending from the neck of the bladder to the tip of glans penis
  • It passes backwards on the floor of the pelvis, turns around the ischial arch forming a sharp bend and then passes forward to be included in the body of the penis
  • It has therefore pelvic and extra pelvic or penile parts
  • The pelvic part is 12 cm long and is relatively small and uniform in diameter
  • The urethral muscle encloses it ventrally and laterally and is very thick
  • It is related to the rectum and prostate above, the obturator muscles below and the Cowper’s gland laterally
  • The extra pelvic or penile part passes between the two crura of the penis turns forward and is included in the body of the penis
  • Here the corpus spongiosum and bulbo-cavernous muscle covers it. The tube forms an enlargement at its beginning, the bulbus urethrae
  • It then gradually diminishes in diameter and very small at its termination, forming processus urethrae
  • The opening from the bladder into the urethra is termed internal urethral orifice, it is closed except during urination
  • The terminal opening is known as external urethral orifice.
  • The colliculus seminalis is a rounded prominence, situated medially on the dorsal wall about 5 cm behind the internal urethral orifice and on it are two slit-like openings situated close together
  •  These are the ejaculatory orifices at which the vas deferens and the excretory duct of seminal vesicle open
  • The urethral crest is a median ridge of mucous membrane in the dorsal wall of the urethra
  • The crest extends forward from the colliculus, while two mucous folds pass backward from the colliculus
  • A little lateral and caudal to the colliculus are the openings of the prostate and behind are the ducts of the Cowper’s gland

Species difference

Ram and Buck

  • The urethra lies in a groove on the ventral surface of the corpus cavernosum.
  • Its terminal part projects commonly about an inch and half beyond the glans penis, forming twisted processus urethrae.

Stallion

  • Pelvic part is 10 to 12 cm long and 5 to 6 cm in diameter.
  • The extra pelvic part is 1.5 cm in diameter.
  • The colliculus seminalis presents on either side a small diverticulum in which the vas deferens and the duct of seminal vesicle opens
  • Lateral to this are the openings of the prostatic ducts and further back are openings of the ducts of the Cowper’s gland

Boar

  • It has a very long pelvic part and covered by a thick urethral muscle except dorsally where there is a dense fibrous layer

Dog

  • The bulb of the urethra is well developed

Rabbit

  • The external urethral orifice is placed dorsally and little cranially

Cock

  • Absent
Last modified: Friday, 16 July 2010, 10:37 AM